GPS (Global Positioning System) messaging is a wireless messaging system for location-specific rather than recipient-specific messages. Somewhat like electronic sticky notes, the messages are sent and received by people with GPS locators in their wireless devices; messages are linked to the location of the sender and accessed by any equipped mobile user entering that location. GPS messaging is sometimes called mid-air messaging, because that's where the messages seem to be located. Hewlett-Packard has a prototype GPS messaging system running in its lab in Bristol, England.
GPS messaging is said to have enormous potential for both emergency situations and the less urgent, albeit ongoing, concerns of users. For example, tourists could leave messages outside a restaurant -- either praising it or complaining about it -- that other tourists would pick up when they were in that location, or highway workers could warn people about upcoming traffic hazards by leaving a message that they would receive when they approached a dangerous area. A project called the Nebraska GPS-Messaging and Satellite Voice Communication Demonstration and Field Test recently explored the use of GPS messaging for law enforcement, emergency response, and highway maintenance applications.
Here's how one version works: You upload a message (or perhaps an audio clip or an image); the message is tagged with your current geographic coordinates and stored on a Web page that is linked to those specific coordinates. Then, when anyone with a capable wireless device enters that location, they can access the message, either as text or image on a screen, or as an audio message through an earpiece. When you move from one location to another, the GPS receiver in your device checks the Web site for messages linked to your location and downloads any that are there. In effect, any GPS-resolvable space could have its own Web site that users would enter geographically.